Manually operated grinding attachment



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MANUALLY OPERATED GRINDING ATTACHMENT Filed May 27, 1957 7 1OSheets-Sheet '10 zhven'io/ Valenfme lYm/(o/as l/oe/zsf Aomgy MANUALLYOPERATED GRINDING ATTACHMENT Valentine Nickolas Hoerst, Cincinnati, OhioApplication 27, 1957 Serial No. 661,665 5 Claims. (Cl. 51-219) Thisinvention relates to apparatus for holding and grindingcutting tools forgrinding the cutting edges ablehowever that the surface be convex toprovide more metal adjacent the cutting edge to reinforce the edge andconduct away heat generated in cutting. In a drilling bit for instance,it is highly desirable that distance from the conical plane formed byrotating the cutting edge, to the ground surface increaseuniformly andgradually from the cutting edge to the trailing edge of the surface andfurther that this distance which is called the clearance be uniformalong any radial line on the'surfacerdrawn from the point of the bit.Thepreferable clearance for a bit varies with the metal to be drilled,and in general the softer the metal the greater the clearance should,be.

It is believed that this convexly curved ground surface which greatly,increases the'strength and life of the cut-. ting edge has only beenobtained by careful and skillful hand grinding and by the use of highlycomplicated apparatus in which the surface is ground from the trailingedge to the cutting edge, a procedure which is unsatisfactory in that ittends to chip the cutting edge.

.It is the object of this invention to provide apparatus for holding andguiding a machine tool for sharpening thereof against a. rotatinggrinder whereby'at least one of the. surfaces forming the cuttingeclge'is ground to a conv exly curved surface thus providing-a cuttingedge of {maximum strength and life. 7 v r It is a further object of theinvention to provide apparatus for holding and guiding a machine toolfor sharpening thereof against a grinder whereby a. cutting edge may beformed having anydesired angle relative to the axis of the tool and atleast one of the surfaces forming the cutting edge may be ground to acurved surface having any desired clearance.

Broadlythe invention comprises a frame, a forward block mounted on saidframe having a pair of recesses extending transversely therein, arearward block having a concavely curved Cavasurfaceextending angularlyand transverselythereona rigid cutting tool carrying support a rockermember fixed forwardly to said support having a pair of jaws for rockingengagement with said recesses and a cam follower fixed rearwardly tosaid support arranged to traverse said cam surface.

' The invention w'illbe described with relation to the accompanyingdrawings in which Fig.1 is a side elevation partly in section of adevice in accordance with the invention.

Fig. 2 is a front end elevation of the device.

' Fig. 3 is" a sectional elevation taken along line 3-3,

of Fig. 2.

eotFiglr 2,874,520 Patented Feb. 24, 1959 Fig. 10 is a partial plan viewof the device showing a cutter in grinding position.

- Figs. 11 and 12 are elevational views showing a cutter in position forright hand grinding.

Fig. 13 is a partial plan view of the apparatus showing a cutter in lefthand grinding position.

Fig. 14 is an elevation view of the apparatus shown in Fig. 13.

Fig. 15 is a rear eievation view of the apparatus.

Fig. 16 is a sectional elevation of the cam block showing the mountingthereof and a portion of the cam follower.

'Fig. 17 is a perspective view of an upper slide member with cam androcker blocks thereon.

Fig. 18 is a perspective view of a side plate for the rocker block.

Fig. 19 is a perspective view of a positioning spring for the rockerarm.

Fig. 2D is another perspective view of a side plate for the rockerblock.

Figs. 21, 22, 23 and 24 correspond to Figs. 17, 18,

'19 and 20 respectively but with parts arranged for left hand grinding.

Fig. 25 is an elevation view of the rocking assembly for right handgrinding.

Fig. 26 is a bottom plan view of the structure shown: in Fig. 25.

Fig. 27 is an end elevation of the structure shown in Fig. 25.

Figs. 28, 29 and 30 correspond to Figs. 25, 26 and 27 respectively butwith parts arranged for left hand grinding.

Fig..31 is a front elevation of the tool carrying support may beprovided in the base plate to secure the stud Fixed upon the stud is alower elongated member 13 upon which is slidably mounted'an upper slide14. It will be observed that members 13 and; i 14 are keyed together toprovide longitudinal reciprocat ing movement of the upper slide 14. 7

in adjusted position.

Reciprocating movement is applied to slide 14 by 13 and slide 14intermediate the ends thereof as by a T-bolt 19 and nut 18, such stops17 being mutuallyengageable as shown.

Fixed to the forward end of s1ide'14is an'upright rocker block 20..Block 20 maybe permanently fixed to .Slide 14 or it may be attachedthereto for replacement ,or interchange as desired. The rearward face ofblock. p 20 is provided with a transversely extending slot 27 and t theforward face of block 20 is provided with a trans vcrsely extendingslot: 28. The top and bottom walls of each slot 27 and 28 areirregularly curved as shown.

Fixed permanently or interchangeably, as by bolts 45 to the rearward endof slide-14 is an upright cam block 31 having a cam surface 30. Camsurface 36 is generally concave and its contour is smooth andirregularly curved. It will be observed that the surface 36 faces in agenerally upward and rearward direction. The lower edge of the surface36 is inclined laterally from side to side of the block 31. Thus thesurface 39 is curved in substantially vertical, horizontal and laterallyinclined directions. Development of the cam surface 30 is carried out asa complement to the surface to be ground.

A rocker arm 48 has a depending member 21 at one end thereof fixedpermanently or interchangeably thereto. Member 21 has jaws rockablyengaging the slots 27 and 28 which constitute pathways therefor. Thejaws of member 21 have resilient engagement with the perpendicular wallsof slots 27, 28 by means of pins 22 which are urged into engagement withsuch walls by springs 2.4, each of which bears upon an adjusting screw25. An additional pin 23, with spring 24 and screw 26 may be provided.

Rocker arms 21 has curved longitudinal sides to which the inner surfacesof side plates 32 and 33 correspond. Side plates 32 and 33 are securedto rocker block 20 by suitable fastening means 34. Strip springs 35 and36 are fastened to side plates 32 and 33 centrally thereof by fasteningmeans 37, such springs bearing upon the rocker member 21 to stabilizeits rocking movement.

Rocker arm 48 is also provided with a depending cam follower 29 having alower curved surface for engagement with cam surface 30.

Rocker arm 48 has tool supporting means comprising a V-shaped troughforming, as shown, a 90 included angle. Each wall of the trough has anoutwardly extending flange. A tool 49 to be sharpened is held inposition in the trough by means of front and rearlocking assemblies. Thefront locking assembly comprises a bracket 56 slidable on the flangesand securable thereto by set screw 57 and locking bolt 55 centrally andthreadedly mounted in bracket 56 to abut the top of tool 49. Rearlocking assembly comprises bracket 60 slidable on the flanges andsecured thereon by set screw 57, and locking bolt 59 which carries anarbor 61 for engagement with the end of the tool.

A handle 58 is slidably positioned somewhat centrally on arm 48 and issecurable thereto as by set screws 57.

A positioning member 63 is preferably provided for the tool to besharpened, such member being generally L.-shaped with an included angleof about 135. The member 63 has a slot in one of its arms to receive ascrew 62 mounted in one wall of the tool receiving trough. The other armof member 63 is adapted to bear upon one of they flutes in the tool toposition its cutting edge in generally horizontal position. It will beapparent that the member 63 may be secured in such tool holding positionby tightening the screw 62. The slot in member 63 makes it adaptable foruse with tools of varying sizes.

Insharpening cutters, a bar 54 is secured in the trough of arm 48 andthe cutter 51 (see Figure is mounted conventionally in the bar 54 as byset screw 53. obvious that thebar 54 may be bent at right angles formounting milling cutters and the like for sharpening.

For sharpening left handed tools, a structure such as shown in Figures21 to 24 and 28 to 30 is employed,

such structure being similar in all respects to that already describedbut in which the various parts are reversed. Instead of rocker block 20,a block 40 is employed with slots or-recesses 38 and 39 inreversely'directed position. Instead. of cam block 31, cam block 42 withcam surface 41 is used. Similarly,,rocker jaw member 47. and

It is cam follower 46 are employed on rocker arm 48, plates 32 and 33vbeing interchanged.

Preferably, cam surfaces 30 and 41 are formed on separate plates asshown in Figure 16, such plate being adjustable relatively to the block31 or 42 by means of screws 44 and being also spring pressed outwardlyas by plurality of coil springs 43 seated in sockets in the block 31 or42. Such a resiliently mounted plate ensures close contact therewith ofthe cam follower as it traverses various portions of the cam surface.

In operation, the tool to be sharpened, such as 49 or 54, is secured inposition in the rocker arm assembly 48. The elevation of the apparatusis adjusted by means of the bolt 12 to position the tool opposite thecircumfcrential face of grinder 50. Then the apparatus is rotatedrelative to the grinder by rotating the stud 11 in its socket to set thecutting edge of the tool at the desired angle to the grinder. Theapparatus is then locked in such position by means of the set screwprovided.

The desired clearance setting is obtained by adjusting the screws 44 incam plate 30. To increase the clearance the screws 44 adjacent thelongcurve or wide side of the cam surface are loosened and the springs 43force the cam plate outwardly. The grinder being rotated, the handle 58is manually manipulated to rock the tool carrying assembly.

The cam follower 29 moves in a three dimensional curved path over camplate 30 and the rocker arm rocksin recesses 27 and 28 and betweenplates 32 and 33. The cuttingedge of. the tool is thus moved in a curvedpath including vertical, transverse and longitudinal move-. mentrelative to the grinding face to obtain a sharpened cutting edge at thedesired angle to the axis of the tool, and a convexly curved surfacehaving the desired clearance. The tool may be rotated in the trough topresent another cutting edge for sharpening.

The path of movement of the surface to be ground against the grinder isgoverned by the curvature of cam plate 30, and the curved faces ofrecesses 27 and 28 and rocker member 32. These curves are machined in relation to known mathematical formulae and will vary in size and shapewith the diameter of the grinder.

The use of apparatus which provides for substantially ertical movementof the cutting face of the tool with respect to the grinding wheel (ascompared with conventional crosswise movement with respect to the wheel)results in the production of the greatly improved convex cutting face asset forth. Moreover, the apparatus described makes it possible to grindcutters with a convex cutting face rather than the conventional fiat orconcave cutting face on such tools.

I claim:

1. In sharpening apparatus for cutting tools, a device for holding andguiding a cutting tool comprising a supporting plate, a rocker blockfixed to one end of said plate, a cam block fixed' to the other end ofsaid plate and having a generally concave irregularly curved camsurface, a cutting tool support having a depending jaw member at one endrockably engaging said rocker block and a depending cam follower at theother end for sliding engagement with said cam surface to guide rockingmovement of said support, said cutting tool support being freely and.manually movable in any path determined by engagement of said camfollower with said cam surface, and a handle fixed to said cutting toolsupport for effecting manual movement thereof.

2. A device for holding and guiding a cutting tool as defined in claim1, said camblock having a resiliently mounted plate on which. said camsurface is formed.

3. A device for holding and guiding a cutting tool as defined in claimv1, saidrocker block having a pair'of transversely extending slots andsaidjaw member-having jaws extending into said slots. I

4. A devicefor holding and guiding, a euttingtool as defined in claim 1,said rocker block having a of:

transversely extending slots, each said slot having irregularly curvedwalls, said jaw member having jaws extending into said slots andresiliently mounted portions engaging said slot walls.

the other end of said supporting plate and having a concave, irregularlycurved, cam surface, a rocker arm having a depending jaw member rockablyengaging said rocker block and a depending cam follower arranged toslidably engage said cam surface, and means carried by said rocker armfor clamping tool thereto.

References Cited in the file of this patent UNITED STATES PATENTS2,178,441 Swanson Oct. 31, 1939

